Air-to-air heat pump apparatus



Aug. 21, 1956 AIR-TO-AIR HEAT PUMP APPARATUS Filed Feb. l5, 1954 R. H.BURGESS '7 Sheets-Sheet l Aug, 2l, 1956 R. H. BuRGL-:ss 2,759,334

AIR-To-AIR HEAT PUMP APPARATUS Filed Feb. l5, 1954 7 Sheets-Sheet 2 Aug.2l, 1956 R. H. BURGESS 2,759,334

AIR-TO-AIR HEAT PUMP APPARATUS Filed Feb. l5, 1954 7 Sheets-Sheet 3 ZJLZZ532 296/ Aug. 21, 1956 R. H. BURGEss AIR-To-AIR HEAT PUMP APPARATUS 7Sheets-Sheet 4 Filed Feb. 15. 1954 Aug 21, 1956 R. H. BURGEss 2,759,334

AIR-TO-AIR HEAT PUMP APPARATUS Filed Feb. l5, 1.954 7 Sheets-Sheet 5 250 F157 Z7. Z

Aug. 21, 1956 R. H. BURGESS Ara-To-AIR HEAT PUMP APPARATUS 7Sheets-Sheet 6 Filed Feb. 15, 1954 Aug. 21, 1956 R. H. BURGESS 2,759,334

AIR-TO-AIR HEAT PUMP APPARATUS Filed Feb. 15, 1954 FIEEB 7 Sheets-Sheet7 206 fac zoazm' :755 g Jc 62256 Z, 214

United States Patentl O 2,759,334 AIR-To-Am HEAT PUMP APPARATUS RussellH. Burgess, Chicago, Ill., as'signor to DryingSystems, Inc., Chicago,Ill., a corporation of Illinois Application February 1s, 1954,serial'No. 410,160

Claims. (Cl. 62-4) This invention relates to air-toeair heat pump-apparatus.

In the use of air-to-a-ir heat pump apparatus forconditioning .airwithin a building, the wide range of heating and cooling requirementshas introduced design problems which have in many instancesresultedinundue cost of manufacture or operation, or which have resultedin unsatisfactory operation in other instances, and' it `is the primaryobject of the presen-t invention to improve apparatus of this kind insuch a way as to simplify the construction `and operation thereof.

In apparatus of the :aforesaid character the heatexchanger in the insideair circuit serves as an evaporator during the summer season so thatmoisture is` condensed thereon, while during certain portions of itsWinter operation, frost tends to form on the heat exchanger inV theoutside air circuit, and in both such instances the problem of disposalor collection of moisture or water is presented. It is therefore a morespecic object of the present invention to enable water from lboth these'sources to' be collected in a common sump; and related objects are toenable this to be accomplished .in such a Way that the collectedmoisture may be utilized for humidiflcation or for evaporative coolingas required, to locate such sump at least partially within the insideair passage;I and to associate a constant-level water supply wi-th suchsump to assure an adequate water supply at all times.

Other and further objects of the present invention Will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment 'of the present invention and the principles thereof and whatI now consider to -be the best Inode in which I have contemplatedapplying these principles. Other embodiments of the invention embodyingthe same'or equivalent principles may be used and structural changes maybe made as desired 'by those skilled in the art with-Y out departingfrom the present invention and the pur view of the appended claims.

In the drawings:

Fig. l is a side elevational view taken partially in vertical sectionand illustrating a heat pump apparatus embodying the features of theinvention;

Fig. 2 is a View taken from the left in 1 and showing details ofinternal construction of the apparatus;

Fig. 3 is a view similar to Fig. 2 and 'showing additional details;

Fig. 4 is a fragmentary perspective view showing the sump and relatedparts of the base;

Fig. 5 is a section-a1 view taken substantially along the line 5 5 ofFig. 4;

Fig. 6 is a sectional view taken substantially. along the line 66 ofFig. 4; y

Fig. 7 is a schematic view illustrating the refrigerant circuit;

of the refrigerant circuit; and

2,759,334 Patented Aug. 21, 19,56

2 Fig. 9 is a wiring diagram illustrating the electrical control circuitof the invention.

General `organization unit 22 thatrests on and completely covers thebase uni-t 21, a compressor and heat exchanger unit 23 that rests on andcompletely covers the unit 22, and an upper duct unit 24` that restsupon the unit 23, and 'these sections or units may be secured in suchrelation by conventional fastening means such as screws, bolts vor thelike. The uni-ts 21; 22, 23'and'24 are so formed and related, as will bedescribed in detail hereinafter, that a generally Ll-shaped inside airpassage 25 is provided including heat exchangers 26 and 27, andagenerally U`shaped outside air passage 28 including heat exchangers 29and 30 is provided.l As will -be hereinafter explained, the presentapparatus may be set selectively for winter operation or summeroperation, and in the winter setting of the apparatus the heatexchangers27 and 26 'act as a common condenser in the refrigerant circuit, Whilethe heat exchangers 30' and 29 in the outside air circuit act as acommon evaporator. Conversely, in the summer setting of the apparatus,the heat exchangers 27 and 26 in the inside air circuit act asevaporators so as to cool the air in the'insidewair circuit, whiletheheat exchangers 3l) and 29 in the outside air circuit serve as a commoncondenser to dissipate'heat tothe air flowing in the outside aircircuit.`

The individual sections or units The base 2l is formed primarily by twoend channels 31 and two Side channels 32'secured together so that theyrest on edgeand define a rectangle. Midway between the side channels 32and parallel thereto, an elongated pan or sump 33 is mounted in fixedrelation to the end channels v31, and throughout a substantial portionof its length the pan 33is of the same depth as the base, as shown inFig. l, while throughout the balance of its length the bottom of the panslopes upwardly so tha-t it will drain toward the deep end. Within thesloping end portion of the pan 33 a central division wall is formed byan inverted U-shaped member 33P that'has its lower edges xed to thebottom wall of the pan and which has its closed upper end disposed inthe plane of the upper edges of the channels 31 and 32. At the left handend of the member 33P, Fig. 4, a cross plate 33E is extended across thepan 33 with its upper edge in the plane 'of the upper edges of thechannels 31 and 32, and its lower edge spaced from the bottom of the pan33 below the normal level of water that is maintained in the sump or pan33, as will be explained hereinafter.

The unit 22 is afforded by a plurality of square tubular frame menrbers39 on which parallel end walls 40 and 41 and an intermediate Wall 42 aresupported, the intermediate wall 42 being spaced from" the end wall 40so that the intermediate wall 42 will be disposed directly over and willengage the upper edge of the cross plate 33E, Aand on opposite sides ofthe pan 33, this wall 42 rests on channels 44 which extend from the sidechannels 32to the opposite sides of the pan. The unit 22 also has sidewalls 45 and 46 and between the end wall 41 and the intermediate wall42, a heavy insulated vertical wall 47 is provided which rests at itslower edgevon the division wall 33P of the pan or sump'33. In thepresent instance the wall 40 is afforded by doors which extend the fullheight of the sections 22, 23 and 24 so that these doors or walls 40form the front or left-hand wall in 3 Fig. 1, for all of the units. Theunit 22 is thus divided into a pump chamber 48 defined by the walls 40,42 and 46, an inside fan chamber 49 defined by the walls 41,

42, 46 and 47, and an outside fan chamber 50 defined by the walls 41,42, 47 and 45.

Within the pump chamber 48 a water pump 51 is supported with an intakepipe 511 projecting downwardly into the sump 33. This pump 31 is drivenby a motor 51M, and its discharge passes through a pipe 51D to its pointof use, as will be described hereinafter.

Within the inside fan chamber 49, an inside blower or fan 52 is mountedon support bars 52B, so that the discharge 52D of the fan opens upwardlyadjacent to the wall 47. Similarly, an outside blower or fan 53 ismounted on supports 53B in the chamber 50 so that the discharge 53D isdirected upwardly adjacent to the other side of the wall 47. The fans 52and 53 are driven by belt connections from drive motors 52M and 53M thatare supported from cross bars 52B and 53B in the chambers 49 and 50 ofthe unit 22. The chambers 49 and 50 constitute portions of therespective inside and outside air passages 25 and 28 and cooperatingportions of these passages are formed in part in the unit 23 and in partin the unit 24, as will now be described.

The unit 23 also has a framework formed from square tubular members 59closed at its forward end by the wall afforded by the doors 40 and onwhich an end wall 61 and an intermediate wall 62 are mounted in parallelrelation, so that the intermediate wall 62 is substantially above thewall 42. The unit 23 has side walls 65 and 66, and between the wall 62and the end wall 61, a thick insulating wall 67 is mounted so as to reston and form an upward continuation of the wall 47. Midway between thewalls 66 and 67 a vertical division wall 68 is extended parallel to thewalls 66 and 67 thus to afford a downward passage 25D between the walls66 and 68, and an upward passage 25U between the walls 68 and 67.Similarly, a wall 69 is mounted midway between and parallel to the walls65 and 67 to dene a downward passage 28D between the walls 65 and 69 andan upward passage 28U between the walls 67 and 69. In the lower endportion of the passage 28D, the heat exchanger 29 is mounted; 1n theupper end of the passage 28U the heat exchanger 30 1s mounted; in thelower end of the passage 25D, the heat exchanger 26 is mounted; while inthe upper end portion of the passage 25D, the heat exchanger 27 ismounted; and these heat exchangers function in the operatlon of the heatpump system, as will be hereinafter described. Above the heat exchanger29 and in the passage 28D, a spray nozzle 75 is mounted and is connectedto the discharge 51D of the water pump 51 so that the heat exchanger 29may be caused to function as an evaporative condenser, as will bedescribed.

The passages 25U and 28U have their lower ends partially closed by crosswalls 68W and 69W, each of which has a relatively large opening therein,these openings belng connected to the respective discharge ends of thefans 52 and 53 by fiexible sleeves 52F and 53F.

The space defined by the walls 4t), 62, 65 and 66 constitutes acompressor chamber S and has bottom and top walls 81 and 82 so as toconstitute a close chamber, and since the doors 40 may be opened atwill, an inside stationary wall 60 is provided just inside the doors 40.The wall 60, as well as all of the other walls defining the compressorchamber 80, are lined with sound absorbent material so as to eliminateobjectionable noise transmission. Within the compressor chamber 80,first and second motor driven compressors C-l and C-Z are mounted, alongwith a considerable portion of the refrigerant piping and control meansincluding a four-way control valve 84 and a suction gas superheaterafforded by a heat exchanger 85 suspended above the compressors C-1 andC-2 and functioning as will be described hereinatfer to dissipate andeifectually utilize the heat of the C0111- pressors.

The upper unit 24 of the structure is afforded by a framework made fromsquare tubular members 89 having its forward end closed by the walls ordoors 40 and having an end wall 91 and an intermediate wall 92 whichfalls substantially in the plane of the wall 62. Side walls 95 and 96are also provided and between these side walls a heavy insulateddivision wall 97 is provided which rests on and forms an upwardcontinuation of the wall 67. Between the walls 96 and 97 a division wall98 is afforded which rests on the wall 68 and forms an upwardcontinuation thereof; and similarly, a wall 99 is afforded so as to reston and from an upward continuation thereof. The side wall 95 is arrangedin the present instance to afford an intake passage or opening 95Athrough which outside air may enter to pass downwardly through thepassage 28D, and the top of the unit 24 between the walls 95 and 96 isin this instance closed by a top wall 100. Between the walls 97 and 99the top wall 100 has a discharge opening 28-2 from which such outsideair may be discharged after use. Similarly, the top wall 100 closes theupper side of the unit 24 between the walls 96 and 98, while a dischargeopening 25-2 for the inside air circuit is afforded in the wall 100between the walls 97 and 98. The side wall 96, in the form shown, has anintake opening 96A formed herein to which the return pipe of theductwork may be connected. Within the passage 25D and in the spacebetween the walls 96 and 98, an ailfilter 101 is preferably positionedto filter the air passing through the inside air system. The inletopenings for the inside and outside air intake passages may, if desired,be provided in the top wall 100, as indicated in dotted outline at 295Aand 296A in Fig. 3, and in such an instance'the corresponding intakeopening 95A or 96A, or both, would be eliminated through the provisionof imperforate side walls 95 and 96.

Within the inside air passage 25U and disposed above the heat exchanger27, an electric booster heater 105 is mounted so that this heater may berendered operative when additional heat beyond the normal capacity ofthe system is required, or during the defrosting cycle that will bedescribed hereinafter.

The water level in the sump 33 is maintained at a constant level throughthe provision of a water supply line 107 and a float control valve 10Swhich, with its controlling float 108F, is mounted on the lower surfaceof the pump support platform. The sump 33 is also provided with anoverflow 109.

The sump 33 is arranged to receive and collect condensate that may beformed on any one of the heat exchangers 26 to 30, and for this reason adrip pan 110 is mounted in the outside fan chamber 49 beneath thesupport 53B, while a similar drip pan 111 is mounted in the inside fanchamber 50 beneath the supports 52B. These drip pans slope toward thesump 33 and are arranged to discharge the collected water into the sump.

Within the inside air passage 25, and associated with the sump 33, is anupstanding humidifier plate of an absorbent material, having a wick-likeaction, and this plate is mounted so that its lower edge is disposed inthe sloping portion of the sump 33 below the normal water line that ismaintained therein. The humidifier plate 115 extends upwardly for asubstantial distance into the chamber 49 so as to be subjected to airflow, and is notched at 115N along its lower edge to afford clearancefor the fan supporting bars 52B. The humidifier plate 115 attains itshumidifying action in such a way as to afford the desired humidity inthe air circuit within a range variation that is satisfactory in manyinstances. Under other instances, however, it may be desirable to attaina more accurate regulation of humidity, and in such an instance, thewall sections 68W in the inside air circuit are constituted in the formof pans to which a constant but relatively small supply of water issupplied, and the control of humidity is attained through theassociation of an intermittently operable electric heater 115H with eachof the pans 68W. The manner 'of control of the heaters 115H will bedescribed in some detail hereinafter. I t should `be pointed out thatany excess Waterthat may be supplied to the pans 68W merely overflowsonto the drain Pan 111 so as to be `dischargld into the sump 33.

The enclosed compressor means Before describing the refrigeratingcircuit in detail, it should be pointed out that under the presentinvention the compressors C1 and C2 arefully enclosed within thecompressor chamber 80,` and this chamber is so constructed that therecan be no appreciable air flow either into or out of the chamber. Withthis arrangement, and through the use of the heat exchanger 85, the heatof the compressors is utilized Under Ithe present invention tocontribute a portion of the heat that is required in the inside airsystem and, as will 'be further explained, the heat exchanger 85 in this4arrangement serves as a superheater for'the return retrigerant'as itapproaches the compressor.

The refrigerant circuits The 4-way valve 8d is of a well known type, andserves as the primary governing means for determining'the 'ow path ofthe refrigerant in the present system. This 4- wayv valve is actuatedbetween its two positions by means of a pilot valve 84P, which isshifted between its two ef fective positions by means of a solenoid 84S,andthe'way in which this solenoid is controlled will be described here#inafter.

The refrigerant that is being returned to `the compressors C1 or C2flows from' the 4-wayvalve 84 through a line 118 to one end of thesuper-heater 85, and any liquid components of the refrigerant that arethus fed to the super-heater 85 are evaporated within the superheaterand pass to a Isuction line 119 that has branches 119-1 and 119-2, whichconvey the low pressure gaseous refrigerant to the respectivecompressors C1 and C2. The refrigerant gas is compressed within one orthe other,

or both, of the compressors, the suction pressures of which areequalized by an equalizing line'120. Compressor discharge is fed throughhigh pressure lines 121-1 and 121-2 to a common hot gas line 121thatextendsto the 4-way control valve 84." In one setting of the 2t-wayvalve 84, this hot gas is fed through a line 122 to the upper or intakeheader 30-1 of theheat exchanger 30.'

Asv it passes through the heat exchanger 30, the gas is subjected to acondensing action, and passes to a common header 29-.30H whichconstitutes the' lower header for the heat exchanger 30 and the upperheader for lthe heat exchanger 29. The gaseous and condensed portions ofthe refrigerant then ow to a lower header 29-2 ofthe heat exchange unit29, and pass through'a pipe 124 to a 3-way' hand valve 123 and to a line125. This line includes a check valve 130, a filter-dryer unit131 and anexpansion valve 132, from which the expanded gas flows toa 3-wa'y handvalve 133 and through a pipe 134 to the lower header 26-2 of theheatexchange unit 26; The expansion valve 132 is controlled ina conventionalmanner by a control element 132C1that is associated with the return orsuction line118` (see Fig. 7). vThe refrigerant Vthat is thus suppliedto the heat exchanger 26 passes through this heat exchanger and `acommon header 26-271-1 to the lower end of the heat exchange unitV 27,and in passing through theunit 27, the evaporation is substantiallycompleted and the gaseous refrigerant and the remaining unevaporatedportions thereof pass into an upper header 27-1 of the `unit27andthrough a return pipe 135 to the 4-way valve S4. The action of thesystem in the summer setting thereof is therefore Vto cool the airpassing through the inside air passage 2 5.

In the winter setting of the 4wafy valve ,84the'hot gases under pressurefrom 'the compressorsv pass ythrough thelirie 135 and throughy the heatexchange units 27` and 26fin succession,l Iso that: the'hot gas islcondensed, and since this condensing action is obtainedby air flowthrough @esegesi the inside' air passageZS, this serves to heat the airin the inside air system, The condensed refrigerant then passes throughthe line 134 and the hand'valve 133,l but since it cannot flow throughthe check valve 130, this condensed or liquid refrigerant is transmittedthrough a line 136, a check valve 137, a filter-dryer unit 138, anexpansion valve 139 and a pipe 140 to the 3-way valve 123 from which itpassesthrough the line 124 to the lower header 29-.12 of the heatexchange unit 29. This refrigerant then passes Vthrough the heatexchange units 29 and 3i?, and since for winter operation the system isset, as will hereinafter be described, so as to supply such liquidrefrigerant to the heat exchangers 29 and 30 at a temperature which lisfifteen to twenty degrees below the minimum outside air temperature, therefrigerant will absorb heat from the air flowing through the outsideair system of the apparatus. This is effective to evaporate a largeproportion of the refrigerant, and this evap- Orated refrigerant, alongwith the entrained unevaporated portions thereof, will pass though. theline 122 to the 4- way control valve 84 which in this winter settingtransmits the refrigerant to the suction line 118 and the superheater 85so that after superheating, the gaseous refrigerant is returned to theintake of the compressor through the line 119. The expansion valve 139is governed in a conventional manner by a control unit 139C that isassociated with the scution line 118 adjacent to the control unit 132C.s v

The pilot valve 841 has a control connection 84-1 vto the main valve`84, and pressure connections for the pilot valve 341? are afforded bypipes 84-2 and 84-3 extended respectively to the return line 118 and thehigh pressure line 121-1,

The pressure operated controls For control purposes that will bedescribed in further detail hereinafter, a high 'pressure control line142 is extended from the highpressure line 121-.-1, and has a pressureoperated high limit switch 143 associated therewith. The line 142also'has a pressure operated switch 144 connected theretofor the purposeof controlling the inside fan 5,2, as will be described. A pressureoperated switch 145 is also associated with the high pressure line 142for the purpose of controlling the pump 51 that supplies lwater to theevaporative condenser, and this action will be described hereinafter.

A low pressure control line 146 is connected to the intake of thecompressor C-2 so as to be thereby associated with the suction line 119,and this low pressure line 146 has a pressure switch 147 associatedtherewith that is effective to control the operation of the secondarycompressor C-2 so as to start the compressor C-2 when the return linepressure is reduced to such a level as to indicate the need for addedcompressor capacity in the system.

A third control pressure line 148 is connected to the gas line 122 andthis line is utilized to govern the operation of a pressure switch 149which, in turn, serves as a primary control for governing the automaticdefrosting operation of the system. The pressure switch 149 is of the'snap acting type arranged at an adjustably set low pressure to snap toits low pressure position, and at an adjustably set high pressureposition to snap to its high pressure position. The pressure switch 149is connected to the line 148 througha check valve 150 and a springbiased relief valve 151 connected in parallel, the check valve 15d]being arranged to permit How of gas from the pressure switch 149 to theline 148, while the relief valve 151 is an adjustable spring-loadedvalve arranged to prevent ow of gas from` the pressure switch 149, andto allow ow of gas to the pressure switch 149 when the pressure of suchgas in line 148 reaches a predetermined value, and the, relationship Yofthe Snap acting pressure switchf149, the check Valve 150 and the reliefvalve 151 is utilized to govern the starting time and length of thedefrosting cycle and the pressure settings of the switch 149 and therelief valve 151 will be described hereinafter as they are related toeach other and to the refrigerant circuits attaining this result.

The pressure switches just described are included in the main electricalcontrol circuit of the system, as will now be described.

The electrical control circuits The electrical power for operating andcontrolling the present system is illustrated in Fig. 9 as beingafforded by a 220 volt 60 cycle lphase circuit having a common wire 160and two other wires 161 and 162. The compressor C1 is arranged to beenergized through a magnetic contactor C-1S, while the compressor C-2 isarranged to be controlled by a magnetic contactor C-ZS, and these twocontactors are connected to the 220 volt l-phase circuit in aconventional manner, as illustrated in Fig. 9. Similarly, the motor forthe outside air fan 53 is controlled by a magnetic contactor 53S, whilethe motor for the inside fan 52 is governed by a magnetic contactor 52S,and these contactors are connected to the 220 volt l-phase circuit inthe conventional manner. Another contactor 1058 is also afforded forcontrolling the inside air heater 105, and this contactor is alsoconnected in a conventional manner The magnetic contactors and theheater 1151-1 constitute the primary elements that must be governed andcontrolled in the automatic operation of the present system, and suchcontrol is attained through a low voltage control circuit that obtainsits low voltage from a transformer 163, the primary of which isconnected between the wires 160 and 161. The secondary of thetransformer is connected to leads 164 and 165 between which the variouscontrol circuits are disposed.

The primary setting control for the present system is afforded by a4-position rotary switch 166 that has its common Contact connected tothe wire 164 by a wire 167. The settalble contact for the switch 166 isafforded by a cross bar 166M that may be set in any one of fourpositions. In addition to the olf position, the switch has an onposition, a winter position indicated by the letter W and a summerposition indicated by the letter S. In the winter position, the movablecontact 166M extends circuit from the wire 167 to two opposite Wcontacts, and from the upper one of these W contacts wires 168 and 169extend in series to one end of a relay coil 170C, the other end of whichis connected by a wire 171 to the Wire 165. Wires 172 and 173 extendfrom the wire 169 respectively to the on position and the summerposition so that when the cross bar 166M is in either the on position,the winter position or the summer position, the coil 170C will beenergized. The other stationary W contact of the switch 166 is connectedby a wire 174 to a terminal 175, and between this terminal 175 and thewire 165, a relay coil 176C is connected. Similarly, a relay coil 177Cand a relay coil 178C are connected in parallel between the terminal 175and the wire 165. Thus, in the winter position of the switch 166, thecoils 176C, 177C and 178C will be energized, and this is in addition tothe energization of the coil 170C.

Also connected in the low voltage circuit are the main sensing controlsthat sense conditions in the conditioned space for governing theoperation of the system. Thus, a main thermostat 180 is connectedbetween the wire 164 and a terminal 181, and relay coils 182C, 183C and184C are connected in parallel between the terminal 181 and the wire165. Thus, upon closure of the main thermostat 180, these three relaycoils will be energized. A humidistat 185 is also connected at one ofits terminals to the wire 164, and between the other terminal of thehumidistat and vthe wire 165, a relay coil 186C is connected so thatthis coil will be energized when sensing of the need for humidicationcauses the humidistat 185 to close. A secondary or sub-thermostat 188 isconnected at one of its Iterminals to the wire 164 and from the otherterminal of the secondary thermostat 188, a relay coil 187C is connectedtothe wire 165. The thermostats and 188 are of the type which closetheir contacts upon a drop in temperature to a predetermined level, andsuch thermostats may be of any conventional type arranged to aiford aworking differential whereby the thermostat opens circuit at a slightlyhigher temperature level. The thermostat 180 is mounted in the usualposition on an inside wall of the building that is being conditioned,while the sub-thermostat 188 is mounted on the inside surface of anoutside wall and near the iioor of a room. The location of thesub-thermostat 188 is preferably on the outside where the greatest heatloss may be expected, and the thermostat 188 is set about 5 degreesbelow the setting of the thermostat 180 so as to attain a highlyadvantageous heat control in winter, as will be explained.

The relay coils that have thus been described serve to controlcorrespondingly numbered relays shown in Fig, 9 which, in turn, governthe energizing coils of the dilferent magnetic contactors.

Conditioning relays 170, 176, 177 and 178 are provided which are undercontrol respectively of the relay coils 170C, 176C, 177C and 178C, andall four of these relays are of the single pole double throw type, andare arranged so that the contact bars thereof are disposed normally inthe lower position shown in Fig. 9 and are actuated to their upperposition when their respective coils are energized. A wire 190 extendsfrom the wire 162 to one of the upper contacts of the relay 170, while awire 191 extends from the other upper contact of the relay 170, and hasbranch leads extended therefrom to one upper and one lower contact ofeach of the relays 176 and 177. The other lower contact of the relay 177is connected by a wire 193 to one end of the operating coil 52C of themagnetic contactor 52S of the inside fan 52. Thus, when the relay 170 isenergized and the relay 177 is de-energized, the inside fan 52 will beoperated, and this condition prevails when the main control switch 166is in its on position.

The other upper contact of the relay 177 is connected by a wire 194 toone contact of the pressure operated switch 144, the other contact ofwhich is connected by a wire 194B to the wire 193. Thus, when the relay177 is in its upper or winter position, and the conditioning relay 170is in its upper or winter position, the inside fan is placed undercontrol of the pressure switch 144. With this arrangement, the insidefan remains inoperative until pressure in the compressor output line121-1 reaches a predetermined operative level so as to close thepressure switch 144.

The other conditioning relay 178 is connected by a wire 195 to the linewire 162, and this wire 195 has branches extending to one bottom contactof the relay 178. The other bottom contact of the relay 178 is connectedby a wire 196 to one contact of the pressure switch 145, and the wire197 extends from the other contact of the switch 145 to one terminal ofthe motor 51M, the other terminal of this motor being connected to thecommon line wire 160. The actuation of the relay 178 to its upper orwinter position renders the circuit to the motor 51M ineffective, butwhen the relay 178 is de-energized and its common contact is in itslower position, the pump circuit is conditioned for operation undercontrol of the pressure switch 145. This pressure switch is arranged toclose when pressure in the output line 121-1 of the refrigerant circuitbecomes too high, and this causes the pump 51M to pump water through thespray, thus to cause the condenser 29 to operate as an evaporativecondenser.

Control relays 182 and 184 are also provided in the control circuit, andthese relays are of the single pole double throw type, and arecontrolled respectively by the relay coils 182C and 184C. One uppercontact of the relay 182 is connected by a wire 199 to the other uppercontact of the conditioning relay 176, and the wire 199 "nastiest has anextension 199B that extends to the common contact of the pressure switch149. The other upper contact of the relay 182 and the correspondinglowercontact thereof are connected by wires 200 and 201 in series to onecontact of the normally closed safety or overload pressure switch 143,the other contact of which is connected by wire 202 to a `terminal 203.From this terminal, a wire 204 extends to one contact of a normallyclosed thermostatic overload switch 205 that is located in thecompressor C-l, and the other contact of this switch is connected by acontact 206 to one terminal of an operatingcoil CISC that constitutesthe operating coil of the magnetic contactor CIS that governs thecompressor C-. Theother terminal of this coil is connected to the commonline wire 160.

From the terminal 203, a wire 207 is connected to corresponding upperand lower contacts of a conditioningy relay 183 that is governed by therelay coil 183C. The other upper contact of the relay 183 is 'connectedby a Wire 208 to the low pressure contact of the pressure switch 147,and a wire 209 extends from the common contact of the switch 147 to onestationary contact of a time delay relay 210. The other stationarycontact of this relay is connected by a wire 211 to a thermostaticallyoperated normally closed safety switch 212 that is included in thecompressor C-2 and the wire 213 extends from the other contact of thissafety switch to an operating coil C2SC that serves as the operatingcoil for the magnetic contactor C-2S. The other terminal of thisoperating coil is connected to the common linewire 160. The time delayrelay 210 has an operating coil 210C' connected across the twostationary contacts of this relay, and the operation is such that therelay 210 is closed only after a predetermined period, thus to avoidconcurrent starting of the two compressors.

The other stationary contact of the pressure operated switch 147 isconnected by a wire 214 to the other lower contact of the relay 183, andthus the switch 1'47 causes operation of the second compressor inresponse to low pressure in the suction line 119 during the winter'operation vof the system, and in response to high pressure in the line119 during summer operation of the system. l

The other lower contact of the control relay 182 is connected by wires220 and 221 to the other lower contact of the conditioning relay 176,and a branch lead 222 extends from the wire 221 to one lower contact ofthe control relay 184. The other lower contact of the relay 184 and thecorresponding upper contact thereof are connected by a wire 223 to oneterminal of the operating coil 538C, which serves to operate the'magnetic c'ontact'or 53S that controls the outside fan 53. The iotherterminal of the :coil 535C is connected to the line wire 160. The otherupper contact of the relay 184 is connected by a Wire 224 to the highpressure stationary contact of the pressure operated switch 149, and awire 225 connects this same contact to one terminal of the operatingcoil 84S oftheV magnetic pilot valve 84, the other terminal of operatingcoil being connected to the wire 160. The other :or lbw pressurestationary contact of the switch 149 is connected by a wire 227 to aterminalA 228, and this terminal 228 is afforded in the control circuitfor the insideair' heater 105. This inside air heater circuit may becompleted by movement of the pressure switch 149 to its low pressureposition, or through closure of the secondary of subthermo's'tat 188,and for obtaining controly in response to the operation Vof suchthermostat, a relay 1-87 which is controlled by the ycoil 187C. Thus, ayWire 2304 extends from the" wire 199B to one stationary contact of therelayV 187', and' a wire 231 extends from the other contact of thisrelay to the terminal 228. From the terminal 228, a wire 232 extends toone stationary contact of a normally open holding switch 233 that isarranged to be moved to its closed position as an incident to theoperation of the magnetic contactor C-lS. A Wire 234 extends from theother stationary contact of the switch 233 to one contact of a ow switch235 that is nori to `mally jope'n and is arranged to be closed by airflow in the inside air passage 25. A wire 236 extends from the othercontact of the flow switch 235 to one terminal of an operating coil SCof the magnetic contacter 105S, the other terminal of this coil beingconnected to the wire 160. Thus, when the circuit is closed by theswitch 149 or by the relay 187, the inside air heater 105 will beeffective, it being understood, of course,- that such operation can takeplace only when the conditioning relay 176 is in its upper or winterposition.

The heater 115H that is included in the humidifier has v one terminalconnected by a wire 240 to the line wire 160 and the other terminal ofthe heater is connected to one lstationary contact of a normally openrelay 186 that is arranged to be closed by operation of the voperatingcoil 186C. The other stationary contact of the relay 186 is `connectedby a wire 241 to one stationary contact of a holding switch 242 that isnormally open and which is arranged to be closed as an incident to theoperation of the magnetic cont-actor 52S. A wire 243 extends from the'other contact of the switch 242 to the line wire 162. 'Conventionalcircuit breakers, as shown, are used in the usual manner to protect allmotors and branch lines.

Operation The operation of the apparatus is described in all of itsdetail in my copending application, Serial No. 389,640, led November 2,1953, `and reference is hereby made to such coperiding application inrespect to such operation. It may be pointed out, however, that when thesystem is be'mg used for. cooling during the summer, the functioning ofthe heat exchangers 26 and 27 as evaporators causes condensation ofmoisture thereon, and this moisture is drained onto the dri-p pan 111from which it runs into the common sump 33, and as an excess of Water isdischarged intol the sump, this may drain through the overflow 109. Thecommon sump l33 also serves to collect the moisture that isdrained tothe drip pan during a defrosting operation of the apparatus in winteroperation thereof. Such frost, ofcourse, forms on the heat exchangers 29and 30 at certainseasons of the year, and the apparatus that has beendescribed hereinabove is automatically operable, as described in detailin my aforesaid copcnding application, to melt this frost so that it maydrain to the sump 33.

The water that is thus collected in the common sump 33 serves asmasource to maintain the humidifying plate in a moist condition so thatduring winter operation of the apparatus, the water from the common sump33i is utilizedy in attaining humidiiication of the air flowing throughthe inside air circuit. The float control valve 108 serVCS, ofcourse, toreplenish the water supply in the sump 33 in the event that the moistureattained through the defrosting operation is insufficient, and thushumidiiication isassured throughout the entire heating season.

Duringthe summer or cooling season, the cooling load ma-y in someinstances require operation of the heat exchanger 29 as an evaporativecooler, and the common sump 33also serves asa source of water for suchevapora'- tivey cooling operation, such operation being automaticallygoverned by the described apparatus inthe specic manner described in myaforesaid copending application.

Conclusion Frfomthe foregoing description it will b'e apparent that the'prsent invention materially simplifies the construction of air-to-airheat` p'urnp apparatus, and in particular, it will be' evident that thepresent invention enables the moisturefc'ollected inthe various cyclesof operation of the apparatus to be utilized eifectually to assureimproved operation of the apparatus.

Thus, while I have illustrated and described the preferred embodiment ofmy invention, it is to be understood that this is capable of variationand modification, and I therefore do not wish to be limited to theprecise details set forth, but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

l, In an air to air heat pump apparatus having inside and outsideair-circulating passages and a refrigerating system with heat exchangersin said outside and inside air-circulating passages, a common sumplocated in part within a portion of said inside air circulating passageand located in part in said outside air-circulating passage, a porouswick-like humidier plate having a lower edge thereof disposed in saidsump and extending for a substantial distance into said inside airpassage to afford a substantial area Within said inside air passage fromwhich moisture may be evaporated by air ilowing in said inside airpassage, drain pans located below said heat exchangers in both of saidair passages sloping toward and arranged to drain directly into saidsump, oat controlled water supply means operable to maintain apredetermined water level in said sump, an overow for said sump, a spraynozzle located over a heat exchanger in said outside air passage, and apump operable to feed water from said sump to said spray to render saidlast mentioned heat exchanger operative as an evaporative condenser.

2. In an air to air heat pump apparatus having inside and outsideair-circulating passages and a refrigerating system with heat exchangersin said outside and inside air-circulating passages and having controlmeans adapted to be set to summer and winter control positions, a commonsump located in part within a portion of said inside air circulatingpassage and located in part in said outside air-circulating passage, aporous humidifier plate having a lower edge thereof disposed in saidsump and extending for a substantial distance into said inside airpassage to afford a substantial area within said inside air passage fromwhich moisture may be evaporated by air flowing in said inside airpassage, drain pans located below said heat exchangers in both of saidair passages and sloping toward and arranged to drain directly into saidsump, means for maintaining a predetermined water level in said sump,water feed means for spraying water from said sump onto a heat exchangerin said outside air passage to cause said heat exchanger to operate asan evaporative condenser, governing means governed by gaseousrefrigerant pressure in the hot gas portion of said system to controloperation of said water feed means and means operated by said controlmeans to disable said governing means when said control means are insaid winter control position.

3. In an air to air heat pump apparatus having inside and outsideair-circulating passages and a refrigerating system with heat exchangersin said outside and inside air-circulating passages and having controlmeans settable to a summer control position or to a winter controlposition, a common surnp located in part within a portion of said insideair circulating passage and located in part in said outsideair-circulating passage, a porous wick-like member having a lowerportion thereof disposed in said sump and having other portionsextending for a substantial distance into said inside air passage toafford a substantial area within said inside air passage over which airpasses in flowing through said inside air passage to evaporate moisturefrom said member, drain pans located below said heat exchangers in bothof said air passages and sloping toward and arranged to drain directlyinto said sump, means operable to maintain a predetermined water-levelin said sump, water feed means including a spray nozzle located over aheat exchanger in said outside air passage for spraying Water from saidsump onto said last mentioned heat exchanger to render the sameoperative as an evaporative condenser and means governed by said controlmeans for disabling said water feed means when said control means areset to said winter control position.

4. In an air to air heat pump apparatus having inside and outsideair-circulating passages and a refrigerating system with heat exchangersin said outside and inside air-circulating passages and having controlmeans settable to a summer control position or to a winter controlposition, a common sump located in part within a portion of said insideair circulating passage and located in part in said outsideair-circulating passage, a porous humidifier member having a portionthereof disposed in said sump and having another portion extending for asubstantial distance into said inside air passage to afford asubstantial area within said inside air passage from which moisture maybe evaporated by air flowing in said inside air passage, a drain panlocated below said heat exchanger in said outside air passage andarranged to slope toward and to drain the condensate or Water resultingfrom defrosting directly into said sump, drain means located below theheat exchanger in said inside air passage and arranged to receivecondensate and drain the same into said sump, means for maintaining apredetermined water level in said sump, water feed means for sprayingwater from said sump onto a heat exchanger in said outside air passageto cause said heat exchanger to operate as an evaporative condenser,sensing means for sensing the pressure of refrigerant supplied to saidsystem, means governed by said sensing means to control operation ofsaid water feed means, and means governed by said control means fordisabling said water feed means when said control means are in saidWinter control position.

5. In an air to air heat pump apparatus having inside and outsideair-circulating passages and a refrigerating system with heat exchangersin said outside and inside air-circulating passages and located in partin said outside air-circulating passage, a common sump located in partwithin a portion of said inside air circulating passage and located inpart in said outside air-circulating passage, a porous wick-like memberhaving one portion thereof disposed in said sump and another portionthereof extending for a substantial distance into said inside airpassage to aiord a substantial area within said inside air passage fromwhich moisture may be evaporated by air flowing in said inside airpassage, drain pans located below said heat exchangers in both of saidair passages and arranged to slope toward and to drain directly intosaid sump, float controlled water supply means operable to maintain apredetermined water level in said sump, an overflow for said sump, aspray nozzle located over a heat exchanger in said outside air passage,a pump operable to feed water from said sump to said spray to rendersaid last mentioned heat exchanger operative as an evaporativecondenser, sensing means operable to sense the pressure of refrigerantsupplied to said system, means governed by said sensing means to controlsaid pump and means governed by said control means to disable said pumpWhen said control means are in said winter control position.

References Cited in the le of this patent UNITED STATES PATENTS2,243,478 Knoy May 27, 1941 2,297,928 Wilson Oct. 6, 1942 2,309,165Candor Jan. 26, 1943 2,633,004 Leeson Mar. 31, 1953 2,681,182 McGrathJune 15, 1954

